Sensitizing silver-halide emulsions



Ag. 18, 1936. wl DIETERLE ET AL, 2,051,134

SENSITIZING SILVER HALIDE EMULSIONS Filed Jan. ll, 1952 Patented Aug. 18, 1936 UNITED ISTATES SENSITIZIN G SILVER-HALIDE EMULSIONS Walter Dieterle and Walter Zeh, Dessau in Anhalt, Germany, assignors'to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of New York Application January 11, 1932, Serial No. 586,055 In Germany January 10, 1931 10 Claims. (Cl. 95-7) (Granted under the provisions of sec. 14,

act of March 2, 1927; 357 0. G.

Our present invention relates to sensitizing of photographic emulsions.

One of its objects is to provide such an emulsion the sensitivity of which is raised over the range 5 of Wave lengths to which the emulsion is normally sensitive. Further objects will be seen from thel detailed specification following hereafter.

Reference is made yto the accompanying drawing in which Fig. 1 represents an unsensitized silver-bromide emulsion and Fig. 2 the same emulsion sensitized with our new sensitizing dyes.

We have found that a silver-halide emulsion containing a selenoisocyanine corresponding to the general formula Formula 1 V and W=H, alkyl, oxalkyl, substituted amino groups, benzene, halide 30 r and 1"=a1kyl,

A=H, alkyl X=halide, perchlorate, para-toluene sulfonate, alkylosulfate, nitrate, l is sensitive to the green and greenish-yellow ,5 region of the spectrum.

The emulsion thus attains a quite remarkable sensitiveness to the region of the spectrum comprising waves of about 500ML to 600ML. Compared with the known dyes containing in their 0 molecule the thiazole nucleus our new dyes containing in their molecule the selenazole nucleus have the advantage that the range of sensibility imparted to the emulsion having incorporated the same is displaced towards the region of the L5 longer waves by about 10ML. 'I'he dyes are especially adapted for orthochromatic sensitizing.

In general Formula 1, V and W may take any position in the benzene nuclei, the 5 and 6 position, and the 6' and 7' position are preferred.

,0 V and W may represent alkyl such as methyl, ethyl etc., or an alkoxy group, for instance, a methoxy or ethoxy grou or a substituted amino group, or halide, or benzene. r and r may be alkyl, for example methyl, ethyl, propyl etc. A

5 may represent H, methyl or ethyl. X can be any suitable anion that will precipitate the dye, for instance, a halide, paratoluene sulfonate, alkylosulfonate, alkylosulfate, perchlorate, nitrate or the like.

In the accompanying graph there are repro- 5 duced two' spectrograms of the same silver-bromide gelatin emulsion.

Fig. 1 represents the intensity curve of a silverbromide emulsion without a sensitizer.

Fig. 2 represents the intensity curve of the same 10 silver-bromide emulsion sensitized with 1.1diethyl 2.4' (6 ethoXy-benzseleno 6' --methylquino) -cyanine-iodide.

Fig. 3 shows the intensity curve of the same emulsion but sensitized with 1.1diethyl-2.4 15 (benzseleno-quino) -cyanine-iodide.

Fig. 4 shows the intensity curve of the same emulsion but sensitized with 1.1diethyl2.4' (6.6-dimethoxy-benzseleno-quno)-cyanine iodide, and 20 Fig. 5 shows the intensity curve of the same emulsion but sensitized with 1-methyl-1-ethy1 2.4- (4.5-benzobenzseleno-6-n1ethylquino) -cyanine-chloride.

In these spectrograms the abscissae are graduated in millimicrons (au) while the ordinates are graduated in divisions denotingthe blackening of the tested film. The blackenings are taken by exposing the film in a diffraction grating spectrograph of Carl Zeiss, Jena, provided with a Rowland di'raction grating and illuminating with a nitra lamp of 100 Watt through a stage slot.

When 'comparing the curves the superiority of our new dyes will be easily-seen. It is seen that the spectrogram of the emulsion sensitized with a selenoisocyanine is distinguished by a characteristic form from the spectrogram of the emulsion which has not been sensitized or has been sensitized with anotherdyestuff. 40

The dyes are obtainable according to the desired solubility in form of the bromide, iodide, perchlorate etc. and are used in a quantity as usual for the known sensitizing dyes.v This Y quantity amounts to about 10 to 20 milligrams per 45 1 kg. of emulsion ready for 'being cast which contains about 9 per cent of gelatin, 4.5 per cent of silver-halide, the rest being water. However we do not wish to limit our invention to the quantities just indicated, the most suitable amount will in each case be found by a few comparative experiments. The dyes may be added to the emulsion in form of solutions. Suitable solvents are the alcohols, for instance, methyl or ethyl alcohol which may be used anhydrous or diluted with water. The dyes are applied to the emulsion during any stage of its production,

however, they are preferably added to lthe -ilnished emulsion before being cast. The dyes `may likewise be added by coating the emulsion with. them or by bathing the nished photographic material in a bath in which the dye is dissolved.

The dyes are suited for sensitizingan emulsion made according to the boiling process as well as for sensitizing an emulsion made according to the ammonia process.

The method of preparing the bases and the dyes from the bases is analogous to known methods. The method of preparing the dyes. is asv follows. 1 molecular proportion of the base, for instance, 2 methyl-naphtho-selenazole-ethyl-ior dide and 2 molecular proportions quinoline-ethyliodide are dissolved for instance in methanol. This solution is mixed with one molecular proportion of sodium ethylate and the mixture is heated for a short time on the steam bath. The dye separates after a short time in form of the iodide and may be recrystallized from ethanol or methanol. According to the desired solubility the dye maybe transformed into the salt of the corresponding acid.

In order to illustrate our invention we enumerate the following dyes which have been prepared according to the method just mentioned.

(1) 1.1'- diethyl-2.4 (benzseleno-quino) -cyanine-iodide corresponding to the formula may be prepared by dissolving a mixture of 3 grams of 2.methylbenzselenazole ethiodide and 3 grams of quinoline ethiodide in 50 cc. of methanol, adding 15 cc. of an alcoholic solution of sodiumethylate and boiling the mixture for about 1 5 minutes. From the mixture which assumes a red color the dye separates in the form of red i'lakes after cooling, on the addition of a few cc. of a solution of potassium iodide. Recrystallization from alcohol yields orange-red little rods.v

Absorption maximum. of the alcoholic solution of the dye: about 510ML. Range of sensibility of a gelatino-silver-bromide emulsion containing about 4 per cent of silver-iodide and havingl incorporated the dye: about 500ML to about 590ML with a maximum at about 538ML.

(2) 1.1' -diethyl-2.4 (benzseleno6 -methylqulii-cyanine-iodide corresponding to the form a may be prepared in the manner described in AExample 1 when using toluquinoline ethiodide instead of quinoline ethiodide. By recrystallization from alcohol the dye is obtained in the form of orange-red prismatic crystals. Absorption maximum of the alcoholic solution of the dye: about 513ML. Range of sensibility of a gelatine-silver- ,selenazole methiodide bromide-emulsion containing about 4 per cent of silver-iodide'and having incorporated the dye: about 500W toy about 595ML with a maximum at about 540W.

methylquino) -mesomethyl-cyanine iodide corresponding to the formula Se 10 A may be prepared in the manner described in Example 1 when starting from 2 ethylbenzand p toluquinolineethiodide. lAbsorption maximum of the alcoholic solution of the dye: about 513W.. Range of sensibility of a gelatino-silver-bromide emulsion containing about 4 per cent of silver-iodide and having incorporated the dye: about 500ML to about 590ML with a maximum at about 538ML. 2,-

(4) 1.1'diethyl2.4'- (6.6f -dimethoxy benzseleno-quino) -cyanine-iodide corresponding to the formula may be prepared in the same manner described in Example 1v when starting from 2-methyl-5- ethoxy benzselenazole ethiodide and p tolu quinoline-ethiodide. Absorption maximum of the alcoholic solution of the dye: about 520 mi. Range of sensibility of a gelatino-silver-bromide emulsion containing about 4 per cent of silver-iodide and having incorporated the dye; about 500ML to about 610ML with a maximum at about 550ML.

(6) 1.1- diethyl-2.4'-(6chloro benzseleno-- methoxyquino)-cyanine-iodide corresponding to the formula CII may be prepared in the same manner described in Example 1 when starting from 2-methyl-5- chlorobenzselenazole-ethiodide and B-methoxyquinoline-ethiodide. Absorption maximum of the alcoholic solution of the dye: about 515ML. Range of sensibility of a gelatino-silver-bromide emulsion containing about 4 per cent of silveriodide and having incorporated the dye: about 500ml to about 590ML with a maximum at about 538ML.

(7) 1.1'- diethyl 2.4-(5 iodo benzseleno-7'- methyl-quino) -cyanine-iodide corresponding to the formula may be prepared in the same manner described in Example l when starting from 2-methyl-5- oline-ethiodide. Absorption maximum of the alcoholic solution of the dye: about 515ML. Range of sensibility of a gelatino-silver-bromide emulsion containing about 4 per cent of silver-iodide and having incorporated the dye: about 500m.; to about 590ml with a maximum at about 538W.

(8) 1-methyl-1'ethyl2.4' (6 methylbenzseleno-5' 6benzoquino)-cyanine-chloride corresponding to the formula may be prepared in the same manner described in Example 1 when starting from 2.5-dimethylbenzselenazole-methiodide and 5.6-benzoquinoline-ethiodide. Absorption maximum of the alcoholic solution of the dye: about 535m. Range of sensibility of a gelatino-silver-bromide emulsion containing about 4 per cent of silver-iodide and having incorporated the dye: about 500ML to about 630ML with a maximum at about 560ML.

(9) 1-methyl-1 ethyl- 2.4 (4.5 benzobenzseleno-G-methyl-quino)-cyanine-chloride corresponding to the formula may be prepared in the same manner described in Example l when starting from Z-methylbenzselenazole-methiodide and p-toluquinoline-ethiodide. Absorption maximum of the alcoholic solution of the dye: about 535ML. Range of sensibility of a gelatino-silver-bromide emulsion containing about 4 per cent of silver-iodide and hav- -ness. Numbering of the selenazole bases is commenced from the selenium atom, and numbering of the dyes is commenced from the nitrogen atom.

What we claim is:

1. A photographic material comprising a silver-halide emulsion containing a selenoisocyanine corresponding probably to the formula V=H, alkyl, alkoxy, halide and benzo,

W=alkyl, alkoxy and benzo,

r and r'=alkyl,

A=H, methyl,

Xzan anion capable of precipitating the dye.

2. A photographic material comprising a silver-halide emulsion containing 1.1diethyl2.4 (benzseleno-quino) -cyanine-iodide corresponding probably to the formula zHs 3. A photographic material comprising a silverhalide emulsion containing 1.1'diethy12.4'-(6 6 dimethoxy benzseleno quino) cyanine iodide corresponding probably to the formula 4. A photographic material comprising a silverhalide emulsion containing 1methyl-1ethyl- 2.4'- (4.-benZobenzseleno-S-methyl quino) -cyanime-chloride corresponding probably to the formula 5. A photographic material comprising a gelatv ino-silver-bromide emulsion containing about 4 per cent of silver iodide sensitized with 1.1'ldi ethyl -2-4'- (benzseleno-quino) -cyanine -iodide corresponding probably to the formula and having Ia range of sensibility from about 500W to about 590W. with a maximum at about 538ML.

6. A photographic material comprising a gelat ino-silver-bromide emulsion containing about 4 per cent of silver iodide sensitized with 1.1di ethyi-2.4'(6.6' dimethoxy benzseleno quino) cyanine-iodide corresponding probably to the formula per cent of silver iodide sensitized with 1niethyl 1'-ethyl2.4' (4.5- benzo-benzseleno 6'- methylquino) -cyanine chloride corresponding probably to the formula. A

4' l 'i'N Hz \3 \C2Hs and having a range of sensibility of from about 500W to about 630M with a maximum at about 15 560ML.

8. A photographic material comprising a silver halide emulsion containing a selenoisocyanine salt.

9. A photographic material comprising a. silver 20 halide emulsion containing a selenoisocyanine salt being substituted at the central carbon atom by an alkyl group.-

10. A photographic material comprising a silver halide emulsion containing a. dye selected from 2 the group consisting of 1-meth'y11ethy1benzse leno-isocyanine salts and 1.1diethy1jienzseleno isocyanine salts.

' WALTER DIETERLE.

WALTER ZEI-I. 

